1. Field of the Invention
The present invention relates to an ultraviolet microscope and more specifically, it relates to an ultraviolet microscope in which a photochemical reaction between ultraviolet light emitted from a light source in an illumination optical system and a contaminant in the atmosphere in the optical path is prevented.
2. Description of the Related Art
There are ultraviolet microscopes through which a specimen is observed by using light in the ultraviolet range or in the deep ultraviolet range (collectively referred to as ultraviolet light). Ultraviolet light in the deep ultraviolet range (deep ultraviolet light) in particular, has a small wavelength and has high energy. When observing or inspecting a specimen through an ultraviolet microscope, a photochemical reaction between contaminants that are not chemically stable contained in the atmosphere at the optical path of the ultraviolet microscope and deep ultraviolet light emitted from a light source may be induced.
The reaction product resulting from the photochemical reaction between the contaminants and the deep ultraviolet light becomes adhered to the surfaces of optical components such as the objective in the optical path of the ultraviolet microscope. The reaction product then causes clouding of the surfaces, which, in turn, leads to lowered optical performance and more specifically, lowered transmittance. The optical components become more clouded as time elapses while the specimen is observed through the ultraviolet microscope.
Accordingly, measures against clouding are taken by, for instance, washing the optical components of the ultraviolet microscope before they are assembled or as they are used as assembled parts of the ultraviolet microscope. However, depending upon the type of reaction product resulting from a photochemical reaction, the reaction product cannot always be washed off the optical components. For this reason, the product life of the optical components of the ultraviolet microscope is bound to be shorter than that of optical components in microscopes that use visible light as the light source.